Poly-as-triazines

ABSTRACT

DISCLOSED ARE POLY-AS-TRIAZINES, SOLUTIONS THEREOF AND PROCESSES FOR PREPARING SAME WHEREIN A DIHYDRAZIDINE AND A BIS-(1,2-DICARBONYL) COMPOUND ARE REACTED IN A SOLVENT SUCH AS M-CRESOL, ANISOLE OR CHLOROFORM. THE POLY-AS-TRIAZINES ARE PARTICULARLY USEFUL IN HIGH TEMPERATURE ADHESIVE, LAMINATING RESINS, PROTECTIVE COATINGS AND FILMS.

Patented Dec. 11, 1973 3,778,412 POLY-as-TRIAZINES Paul M. Hergenrother,Mercer Island, Wash., assignor to The Boeing Company, Seattle, Wash.

No Drawing. Continuation-impart of application Ser. No. 139,884, May 3,1971, which is a continuation-in-part of application Ser. No. 846,576,July 31, 1969, both now abandoned. This application Sept. 8, 1972, Ser.

Int. Cl. C08g 9/06 US. Cl. 260-50 25 Claims ABSTRACT OF THE DISCLOSUREDisclosed are poly-as-t'riazines, solutions thereof and processes forpreparing same wherein a dihydrazidine and a bis-(1,2-dicarbonyl)compound are reacted in a solvent such as m-cresol, anisole orchloroform. The poly-as-triazines are particularly useful in hightemperature adhe sive, laminating resins, protective coatings and films.

CROSS REFERENCE TO RELATED APPLICATION of the formula (R N\ (m).-

N J N N wherein R and R represent the same or different unsubstituted orsubstituted divalent hydrocarbon radicals of 1 to 20 carbon atoms, nequals or 1, and m equals 0 or 1, can be prepared by reactingdifunctional hydrazidines of the formula HN=o-(R )...-0=NH NH HN Hu11TH; with a difunctional substituted glyoxal of the formula O=C(R )nC=O0: H HC=0 at temperatures of 20 C. to 300 C. and preferably 80 C. to 200C. for a period of 2 minutes to 5 hours. In Example 8 of the Culbertsonpatent, the only example pertaining to the preparation of a polymericas-triazine, there is disclosed a method of preparing a preferredpolymer said to have the following recurring unit This method isdescribed as follows:

=Oxamide-dihydrazone (2.05 g.) is dissolved in hexamethylphosphoramide(125 ml., at C.), available from the Dow Chemical Company as Dorcol.p-Diglyoxalbenzene dihydrate (4.00 g.) is added to this mixture. Theresultant solution is heated for 3 hours at 195 C. and then cooled toroom temperature (20 C.). The resultant viscous solution is poured, withstirring, into absolute methanol (700 ml.) and the dark precipitate soformed is collected by suction filtration. The precipitate is washedthree times with absolute methanol and the washed material is driedunder vacuum (0.2 mm. Hg) for 4 hours at C. to obtain a 4.0 g.(theoretical 4.1 g.) yield of dark brown polymer having a melting pointof greater than 450 C. The polymer is soluble in concentrated sulphuricacid and partially soluble in dimethylacetamide, dimethylformamide, andformic acid.

Infrared and ultraviolet spectra studies give absorption bandscharacteristic of the as-triazine ring. Difierential thermal andgravimetric analysis demonstrates that the polymer has excellent thermalstability in both air and nitrogen to over 400 C.

The poly-as-triazines of this invention can also be prepared by thereaction of a dihydrazidine (also diamidrazone) and abis-(1,2-dicarbonyl) compound. However, in contrast to the Culbertsonpolymer, the poly-as-triazines of this invention are amorphous and thusdo not have true melting points, are essentially insoluble inhexamethylphosphoramide, decompose at or below about 400' C., and arepale yellow to yellowish-orange in color.

SUMMARY OF THE INVENTION This invention is directed to poly-as-triazinescomprismg recurring units of the formula R is a divalent radicalselected from I w S I I I m N N N N s 0 (CH and --(CF2)y wherein y is aninteger of from 1 to 12;

R is a divalent radical selected from and -(CH where z is an integer offrom 2 to 12; and

R and R are monovalent radicals individually selected from hydrogen,alkyl of 1 to 12 carbon atoms, phenyl and substituted phenyl.Substituted phenyl radicals from which R and R can be selected cancontain any substantially inert substituents. By substantially inert ismeant substantially inert under polymer forming conditions ornoninterfering with polymer formation. Exemplary of such substituentsare alkyl (e.g., 1 to 4 carbon atoms), CN, COOH, OR or COOR where R isan alkyl (e.g., 1 to 10 carbon atoms), NO Nl-l Cl, -Br, and CFPreferably, the poly-as-triazines of this invention consist essentiallyof from 20 to 10,000 recurring units of Formula I.

The preferred poly-as-triazines of Formula I are those wherein R and Rare selected from alkyl of 1 to 12 carbon atoms, phenyl and substitutedphenyl. An especially preferred class of poly-as-triazines of Formula Iare those wherein R and R are each phenyl radicals. Thesepolyphenyl-as-triazines exhibit superior solubility, oxidativestability, and amenability to processing, i.e., better flow and wettingcharacteristics. High molecular weight [m (0.5% H 80 at 25 C.)=1.3dl./g.] polyphenylas-triazines exhibit solubility characteristics uniquefor all aromatic heterocyclic polymers. These polymers readily formclear yellow to orange viscous solutions at ambient temperature inchloroform, sym-tetrachloroethane, mcresol, or mixtures of m-cresol andtoluene (1:4) at concentrations as high as 30% solids.Polyphenyl-as-triazines have exhibited excellent thermal-oxidativestability at 260 C. in air as determined by isothermogravimetricanalysis on powders and also as determined by retention of film andadhesive properties after aging at 260 C. for 1500 hours. However,significant degradation occurred upon aging only 50 hours at 290 C. asindicated by weight losses of greater than 13%. An especially preferredclass of polyphenyl-as-triazines are those consisting essentially ofrecurring unit of Formula I wherein m is O or 1; R is selected from and---(CF where y is an integer of from 1 to 12; and

R is selected from Preferably, these poly-as-triazines consistessentially of from 20 to 10,000 such units.

This invention is also directed to a process for the preparation ofpoly-as-triazines and solutions thereof comprising reacting adihydrazidine and a bis-(1,2-dicarbonyl) compound in a solvent selectedfrom the group consisting of m-cresol, anisole, pyridine, chloroform,sym-tetrachloroeth'ane, mixtures of the foregoing and mixtures of xyleneor toluene with m-cresol or sym-tetrachloroethane. For reasons discussedin detail hereinafter, it is preferably to employ from 0.5 to 2.5 molepercent excess of one of the reactants.

It is an object of this invention to provide amorphous poly-as-triazinesand solutions thereof. Another object of this invention is to providehigh molecular weight poly-as-triazines having good hydrolytic,oxidative and thermal stability. A further object is to provide hightemperature adhesives, laminating resins, protective coatings, and filmsand membranes. Yet another object of this invention is to providesolutions of high molecular weight poly-as-triazines having solidscontents of from about 10 to 30% by weight and to provide a process bywhich such solutions can be prepared. Still other objects will becomeapparent from the following detailed description of the invention.

DETAILED DESCRIPTION OF THE INVENTION The poly-as-triazines consistingof recurring units of Formula I are prepared by the reaction of adihydrazidine of the formula HN NH l ll HzNHN- R- NHNHz with abis-(l,2-dicarbonyl) compound of the formula 0 O O O R. l Jl R. Jl l R,wherein R, R R and R have the meanings ascribed thereto in reference toFormula I.

The poly-as-triazines of this invention can be prepared so as to containquinoxaline as well as as-triazine moieties. As illustrated in Example13, random-type copolymers can be prepared by reacting abis-(1,2-dicarbonyl) compound with a mixture of dihydrazidine and abis-(odiamine). As illustrated in Example 14, block-type copolymers canbe prepared by combining an oligomeric as-triazine solution and anoligomeric quinoxaline solution. Exemplary of the bis-(o-diamines) whichcan be so employed are those of the formula (IV) NH: NH:

NH, NHn

wherein R is a tetravalent radical selected from @121 seen 8 Jr: CH:

wherein R R and R have the meaning ascribed thereto in reference toFormula I and R, has the meaning ascribed thereto in reference toFormula IV.

As indicated by Formula I, the reaction of the dihydrazidene and thebis-(1,2-dicarbonyl) compound can yield a mixture of isomers, i.e.,-5,5-, -5,6'-, and -6,6'-. The predominant isomer can be predicted basedon a consideration of the relative reactivity of the carbonyl groups ofthe bis-(1,2-dicarbonyl) compound. The presence of isomeric units in thepoly-as-triazines of this invention may be responsible for theiramorphous character, excellent solubility and processability.

Preparation of the polymers of this invention is preferably carried outin a solvent selected from m-cresol, anisole, pyridine, chloroform,sym-tetrachloroethane, mixtures of these and mixtures of xylene ortoluene with m-cresol or sym-tetrachloroethane. Using these solvents,solutions of high molecular weight poly-as-triazines having solidscontents of up to 30% by weight and higher can be readily prepared.Solution polymerization to form poly-as-triazines is generally conductedby adding the bis- (1,2-dicarbonyl) reactant in the form of a solid,slurry or solution to a slurry of the dihydrazidine. The choice ofsolvent, rates of addition and mixing, and reaction temperature areimportant if polymer solutions of the highest quality are to beobtained.

The choice of solvent is governed by the structure of the polymer.m-Cresol is a universal solvent for all the poly-as-triazines. Theremaining solvents referred to previously can also be used in thepreparation of many of the poly-astriazines. The use of mixtures ofm-cresol and xylene in volume proportions of from 2:3 to 3:2 (preferably1:1) has been found to yield polymer solutions of reduced viscosity ascompared to solutions prepared using other solvents of this invention.

The choice of addition rate depends upon the form ofbis-(1,2-dicarbonyl) compound being used. The addition of a solutionshould be effected more slowly than the addition of a slurry or solid.If the addition of the'solution is effected to rapidly, cross-linkingand branching in the polymer can result.

If the reaction temperature is too low, the reaction proceeds at anuneconomically slow rate while at temperatures too high; cross-linkingand branching can occur. The optimum reaction temperature varies withthe reactivity and solubility of the reactants. Preparation of thepolyphenyl-as-triazines of this invention is preferably carried out attemperatures of from about 10 to about 40 C., while the preparation ofthe remaining poly-as-triazines of this invention is preferably carriedout at temperatures of from about 25 to about 75 C.

The poly-as-triazines of this invention may be prepared using a salt ofthe dihydrazidine such as a dihydrochloride. The desired dihydrazidinecompound is generated from the salt in situ during the cource of thereaction. An acid acceptor such as sodium carbonate, sodium acetate,triethyl amine or pyridine can be included in the reaction mixture.

In the following examples all parts and percentages are by weight unlessotherwise indicated. Examples 1 through 5 are directed to thepreparation of various reactants employed in subsequent examples. Theremaining examples pertain to the preparation and characterization ofpolyas-triazines of this invention.

Example 1 Hydrazine hydrate (95%, 20 ml.) was added to a solution of2,6-dicyanopyridine (2.8 gm.) in 250 ml. ethanol at 40 C. The resultingclear yellow solution was stirred at 45-50" C. for two hours to form awhite suspension which was cooled and filtered. The resulting whitesolid was recrystallized from water (250 ml.) to afford pale yellowneedles (3.0 gm., yield) of 2,6-pyridinediyl dihydrazidine, M.P. 230-231C. with decomposition.

Analysis.Calcd. for C H N (percent): C, 43.51; H, 5.74; N, 50.76. Found(percent): C, 43.72; H, 5.76; N, 50.77.

Example 2 Hydrogen chloride was bubbled through a solution ofterephthalonitrile (12.8 gm. 0.010 mole) in absolute ethanol (250 ml.)at 2025 C. for 18 hours to precipitate the di(imino ether hyrochloride)as a white solid. The solid was isolated by filtration and washed withabsolute ethanol to yield 26.2 gm. yield). The di- (imino etherhydrochloride) (20.0 gm., 0.07 mole) was slurried in absolute ethanol(200 ml.) and at 5 10 C., hydrazine (97%; 5.0 gm., 0.15 mole) inabsolute ethanol (20 ml.) and anhydrous sodium carbonate (15.8 gm., 0.15mole) were added portionwise during one hour. The resulting yellowreaction mixture was stirred at 5 C. for one hour followed by pouringinto ice water. The addition of aqueous hydrochloric acid precipitated awhite solid, p-phenylenedihydrazidine dihydrochloride. Thepphenylenedihydrazidine dihydrochloride was purified by dissolving incold dilute aqueous hydrochloric acid and adding excess coldconcentrated hydrochloric acid to re precipitate the dihydrazidinedihydrochloride as a white solid. The dihydrazidine dihydrochloride wasdried over phosphorus pentoxide at ambient temperature under highvacuum.

Analysis.-Calcd. for C H N Cl (percent): C, 36.23; H, 5.33; N, 31.70;Cl, 26.74. Found (percent): C, 35.97; H, 5.46; N, 31.33; Cl, 26.71.

Other dihydrazidines such as the 3,5-pyridinediyl, mphenylene, andhexamethylene were prepared from the reaction of hydrazine with thecorresponding di(imino ether). These dihydrazidines are isolated as thedihydrochloride and can be successfully employed in polymer formation byusing an acid acceptor such as sodium carbonate, triethyl amine, orpyridine in the reaction mixture.

Example 3 p,p'-Diacetyldiphenyl ether prepared by the Friedel- Craftsacetylation of diphenyl ether in methylene chloride was oxidized withselenium dioxide in aqueous dioxane. The crude product wasrecrystallized from a mixture of dioxane and water (2:1) to afford whitecrystals (60% overall yield) of p,p'-oxybis(phenyleneglyoxal hydrate),M.P. 140.5-142 C.

Analysis.Calcd. for C H O (percent): C, 60.38; H, 4.43. Found (percent):C, 60.18; H, 4.41.

Example 4 A solution of diphenyl ether (17.0 gm., 0.10 mole) andphenylacetyl chloride (30.9 gm., 0.20 mole) in methylene chloride (50ml.) was added during 1 hour to a suspension of anhydrous aluminumchloride (26.6 gm., 0.20 mole) in methylene chloride ml.) at 15-20 C.under nitrogen. The resulting brown reaction mixture was stirred atambient temperature for 18 hours followed by pouring onto crushed iceand hydrochloric acid. The organic phase was separated and washedsuccessively with water, aqueous sodium bicarbonate, and water followedby driyng over anhydrous magnesium sulfate. Concentra-' tion to about 74ml. followed by cooling provided a cream colored solid (33.0 gm. 82%yield), M.P. 166l68.5 C. Recrystallization from benzene alforded nearwhite crystals of p,p'-di(phenylacetylphenyl) ether, M.P. 169- 170 C. Toa mixture of selenium dioxide (11.1 gm., 0.10 mole) in glacial aceticacid (150 ml.) at 60 C., p,p'-di (phenylacetylphenyl) ether (20.0 gm.,0.050 mole) was added. The reaction mixture was refluxed for 24 hoursfollowed by a hot filtration. The clear yellow filtrate was concentratedto about 75 ml. and cooled to provide a yellow solid (18.5 gm., 86%yield), M.P. l03-106 C., after thorough washing with methanol.Recrystallization from a mixture of ethyl acetate and n-hexane affordedyellow crystals of p,p'-oxydibenzil, M.P. 108109 C.

Analysis.Calcd. for C H O (percent): C, 77.41; H, 4.18. Found (percent):C, 77.38; H, 4.10.

Example 5 A benzene (300 ml.) solution of the diacid chloride ofp-phenylenediacetic acid (73.0 gm., 0.3 mole) was added during 1.5 hoursto a stirred slurry of anhydrous aluminum chloride (100 gm., 0.75 mole)in benzene (250 ml.) at -20 C. After complete addition, the resultingthick green reaction mixture was stirred at ambient temperature for 10hours followed by pouring into ice water containing hydrochloric acid.The white solid which precipitated was washed successively in a blenderwith water, aqueous sodium carbonate, and water. The resulting whitesolid was dried to yield p-di(phenacyl) benzene (85.0 gm., 85% yield),M.P. 205 207 C. p-Di(phenacyl) benzene (40.0 gm., 0.13 mole) was addedto a slurry of selenium dioxide (29.0 gm., 0.26 mole) in acetic acid(470 ml.) and the reaction mixture was heated to and maintained at thereflux temperature for hours. The hot reaction mixture was treated withcharcoal and filtered hot to yield a clear yellow solution. Dilutionwith water (400 ml.) followed by cooling provided a yellow solid whichwas isolated and washed with methanol. The resulting yellow solid (29gm., 67% yield), M.P. 124-126 C., was recrystallized from a mixture ofbenzene and hexane (1:1) to afford yellow crystals ofp-di(phenylglyoxalyl) benzene (26 gm.), M.P. 125-126 C.

Analysis.-Calcd. for C H O (percent): C, 77.19; H, 4.12. Found(percent): C, 67.08; H, 4.17.

Example 6 p-Phenylenedihydrazidine dihydrochloride was slurried inm-cresol at 10% solid content, at 20 C. A slurry ofp,p-di(phenylglyoxalyl) benzene in pyridine at 10% solid content wasadded over a period of about 5 minutes. The yellowish-orange reactionmixture was stirred at ambient temperature for 18 hourus followed bypouring into a mixture of methanol and water to precipitate a fibrousyellow solid. The solid was washed in a blender successively withaqueous sodium carbonate, water, and methanol, then dried.Poly[3,3-(p-phenylene)-6,6-(p-phenylene)di(5'-phenyl-as-triazine)] andisomers thereof were formed. The polymer may then be advanced bydissolving in m-cresol and heating to 100 C.

Example 7 Poly[3,3'(2",6"-pyridinediyl)-6,6'-(p,p'-carbonyldiphenylene)di(5phenyl-as-triazine)] was prepared by adding p,p'-carbonyldibenzil(4.4643 gm., 0.010 mole) to a solution of 2,6-pyridinediy1 dihydrazidine(1.9322 gm., 0.010 mole) in m-cresol (25.6 ml.) at ambient temperature.After stirring for 0.5 hr. at ambient temperature, a portion of theviscous yellow solution was poured into methanol in a Waring Blendor toprecipitate a fibrous yellow solid. The yellow solid was thoroughlywashed with methanol and dried for 4 hours. at 150 C. in vacuo. Theresulting intermediate yellow polymer exhibited a polymer softeningtemperature of 300309 C. and an inherent viscosity (m 0.5% H 50 at C.)of 0.74.

The remaining m-cresol solution was placed under a nitrogen atmosphereand refluxed (200 C.) for 1 hr. The final polymer was isolated bypouring the viscous yellow m-cresol solution into methanol in a WaringBlendor followed by thorough washing with methanol and drying for 4 hrs.at 150 C. in vacuo. The m in the final polymer was 1.23. Additionalcharacterization is provided in Tables I and 11 below.

Example 8 A series of polyphenyl-as-triazines of the formula ef ard N Nand isomers thereof wherein R is as shown in Tables I and 11 below wereprepared by reacting stoichiometric quantities of 2,6-pyridinediyldihydrazidine with various dibenzils of the formula oo 00 .uaau.

in m-cresol at 20% solids content. At ambient temperature, clear yellowto light orange viscous solutions formed in less than 0.5 hr. Clearlemon yellow films cast from these solutions exhibited good toughnessand flexibility. The polymers were isolated from solution by quenchingwith methanol in a Waring Blendor to provide light yellow fibroussolids. Characterizations of the intermediate polymers after drying for4 hours at 150 C. in vacuo are provided in Table I. The polymersoftening temperatures (PST) reflect the thermoplastic nature of thesepolymers and also is indicative of their good processability. Theintermediate polymers were advanced to final polymers by heating theirm-cresol solutions at the reflux temperature for 1 hr. under nitrogen.Although the final polymers were of relatively high molecular weights,e.g., =L3 dl./ g. (Table I), they exhibited solubility characteristicsunique for all aromatic heterocyclic polymers. The polymers readilyformed clear yellow to orange viscous solutions at concentrations ashigh as 30% solids content in chloroform or sym-tetrachloroethane. In amixture of toluene and m-creso1 (4:1), the polymers readily formed clearsolutions at concentration as high as 20% solids content. In solventssuch as N,N-dimethylformamide, N,N-dimethylacetamide, orN-methylpyrrolidone, the polyphenyl-as-triazines failed to form clearsolution at solids content as low as 1%.

The thermal properties of the final polymers are presented in Table H.The glass transition temperatures (T were determined by dielectric lossmeasurements at a heating rate of 10 C./min. and a frequency sweep of to1000 cycles/sec. on films cast from m-cresol solutions and dried at C.in vacuo for 4 hours. The polymer films were cycled in the dielectrictest apparatus to 250 C. in vacuo to remove residual solvent prior to aT determination. The polyphenyl-as-triazine containing the rigidp-phenylene moiety exhibited the highest T while thepolyphenyl-as-triazines containing flexibilizing moieties such asdiphenyl ether and diphenylmethane displayed lower T s.

The thermal stability of the polymers was determined bythermogravimetric (TGA) and isothermogravimetric analyses (ITGA). Thepolymers undergo a two stage decomposition in both air and nitrogen andexhibit higher apparent stability in air than in nitrogen. Thetemperature of initial weight loss (T and the temperature of the initialbreak (T as shown in Table II is higher in air than in nitrogen for allpolyphenyl-as-triazines except the polymer containing thediphenylmethane moiety.

The polyphenyl-as-triazines exhibited excellent stability at 260 C. (500F.) in air but at 290 C. (554 F.) significant weight losses (13-36%)occurred after 50 hours. Isothermal weight loss data is given in TableII.

TABLE I Final polymer 1 Intermediate polymer Elemental analysis,(percent) R1 PST, (3. linb, dL/g. fllnh, dL/g. Formula C H N 320-329 0.92 1. 32 (CzoHuNrh 75. 87 2. 83 21. 27 O (75. so) (2.85) (21. 34

287-296 0. 84 1. 27 (CnHflNI); 75. 64 2. 81 21. 29 O (75. 80) (2. 85)(21. 34)

270-280 0. 65 1. 18 (CuH fl n 77. 98 4. 17. 65) O (78. 10) (4. 19) (17.71

278-287 0. 85 1. (C:5H2 N1O) 75. 3. 79 17. O (75. 66) (3. 81) (17.

282-290 0. 77 1. 19 (GuHnN S) 73. 3. 67 17. 11 (37. 53) (3. 70) (17. 16)

300-309 0. 74 1. 23 (CzeHfliNyOh 76. 3. 71 17. 19 (76. 17) (3. 73) (17.28)

1 After 0.5 hr. in m-cresol at ambient temperature, dried 4 hr. at 150C. in vacuo.

5 After refluxing in m-cresol under nitrogen for 1 hr., dried as above.

TABLE 1'! Thermogravimetrlc analysis I Isothermal weight loss, percentAir Nitrogen 260 0. (500 F.) 290 C. (554 F.) 8, 1 T2 T T R1 0. 01 0. 0.m. 200 hr. 50 hr. m.

I I I G/lass transition temperature, determined by dielectric lossmeasurements in vacuo at AT=10 CJmin. and

1 Determined using a Dupont 950 thermalgravimetrle analyzer at AT=6(IL/mi n.

I T1=temperature of initial weight loss.

4 T2=polymer decomposition temperature 01 initial break.

As indicated previously, care should be exercised in the selection ofthe solvent, addition time and reaction temperature used in thepreparation of the polymers of this invention. However, even when careis exercised in the selection of the solvent, addition time and reactionsolutions will occasionally exhibit various degrees of gelling or becomeextremely thick and unworkable (e.g., have a Brookfield viscosity ofgreater than 90,000 cps.). The gelling or thickening occurs eitherimmediately after preparation or upon standing, and is particularlylikely to occur when the reactants used are very pure and when themolecular weight of the polymers and the solids content of the solutionare high (i.e., at least 15% by weight). Polyphenyl-as-triazines (i.e.,polymers of Formula I wherein R and R are phenyl) are particularlysusceptible to gelling or thickening. If the reactants used in thepolymer preparation are not of high purity, the gelling problem is lessserious. However, the use of impure reactants is not an attractivesolution to the gelling problem because the oxidative stability andmechanical performance of the final polymer are usually diminished ascompared to polymers prepared from high purity reactants.

In general, stoichiometric quantities of AA-BB type monomers arerequired in the preparation of high molecular weight, condensation typepolymers (excluding those produced by interfacial condensation). -It hasbeen found, however, that exact stoichiometric amounts of reactants neednot be used in the preparation of high molecular weightpoly-as-triazines and that the gelling problem referred to can besubstantially avoided by upsetting the stoichiometry from about 0.5 toabout 2.5 mole percent (preferably 0.5% to 1.0%) in favor of one or theother reactants. The eifect of upsetting the stoichiometry in thepreparation of two polymers of this invention is shown in Tables III andIV. In the experiment summarized in Table III, p.p'-oxydibenzil (ODB)was reacted with 2,6- pyridinediyl dihydrazidine (PDH) to yield apolyphenylas-triazine of the formula (III) and isomers thereof. Exceptwhere indicated'in Table 1 TABLE III Grams (mole) qr s ODB PDH Remarks(ii/E3 1 Viscous"about the consistency of molasses; "fairly vise0us"--pours readily at room temperature.

1 Inherent viscosity, 0.5% H1804 at 25 C. m-Oresol=xy1ene (1:1). 4 At 50.

TABLE IV Grams (mole) 1 ml, ODB PDH Remarks dl./g.

Very viscous"essentially unpourable; "viscous" and "fairly visc0us"-asin Table III.

1 Inherent viscosity, 0.5% H2804 at 25 C. y

In Table V are shown the effects of stoichiometric imbalance upon theproperties of polyphenyl-as-triazines prepared by reactingoxalamidrazone and p,p'-oxydibenzil (20% solids content in 1:1 mixtureof m-cresol and xylene, 0.02 mole scale). It will be noted that, whenthe stoichiometry was upset by 1% in favor of either reactant,relatively high molecular weight polymers (1 dl./g. =l.61 and 1.76)

were obtained and that films prepared therefrom provided high tensilestrengths (14,100 and 14,900 p.s.i.). Even when the stoichiometry wasupset by 2.5%, film forming polymers with of 1.07 and 1.26 wereobtained.

TABLE V Film Solution (tensile Mo.e oi oxelamidrezone per viscosityflinh, strength, 1.000 mole benzil cps. d1. p.s.i.)

1 Brookfield viscosity at 25 C. 1 0.5% m-Cresol solution at 25 C.

Although the oxidative stability of the poly-as-triazines of thisinvention is very good, it can be even further improved by capping theend groups of the polymer chains to provide polymers which contain fewerreactive end groups which would otherwise serve as potential centers toinitiate oxidative degradation of the polymer. Thus, when thestoichiometry is upset to provide polymer molecules rich in hydrazidineend groups, benzil, or another compound such as benzoyl chloride,capable of reacting with the hydrazidine end groups is used to form amore stable moiety such as an as-triazine or 1,2,4-triazole ring. If thepolymer molecules are rich in 1,2-dicarbonyl end groups, then acompound, such as o-phenylenediamine or 2-pyridylhydrazidine, capable offorming a stable end group such as a quinoxaline or as-triazine ringrespectively, is used.

The amount of end-capping compound used can vary from a stoichiometricquantity to a large excess. The excess end-capping reagent can beremoved by precipitation of the polymer or by leaching from a film orcoating prepared from the polymer solution. End-capping can also beemployed advantageously to improve the oxidative stability ofpoly-as-triazines prepared from stoichiometric amounts of reactants.Example 9 illustrates the procedure employed to end-cap apolyphenyl-as-n'iazine of Formula 11 above.

Example 9 pyridinediyl dihydrazidine and p,p'-oxydibenzil. The resultingsolution was divided into two equal portions and o-phenylenediamine(10.81 gm., 0.01 mole) was added to one of the stirred portions.Stirring was continued for one hour and the polymer was then poured intomethanol to precipitate fibrous yellow solids which were dried and thenredissolved in m-cresol solids content). To this solution was then addedbenzil (2.10 gm., 0.01 mole) with stirring. After stirring for one hourthe polymer was poured into methanol and the yellow solids obtained weredried and redissolved in m-cresol (20% solids content). The twosolutions were processed as described above and the results are shown inTable VI.

TABLE VI Isothermal weight loss at 525 F. in

static air (percent) Film properties after 100 and 200 hr. at 525 F. inair Molar ratio ODBzPDH End capping compound 200 hr. 500 hr. 100 hr. 200hr.

0.98:1.00- 8.0 13.2 Brittle, brown Very brittle, dark brown.0.98:1.00--. Benril 1. 7 3. 7 Flexible, tough, light brown Brittle,brown. 1.00:0.98 9- 1 14. 1 Brittle, brown Brittle, dark brown.1.00:0.98 o-Phenylenediamine 1.7 3.5 Flexible, brownish orange--- Do.1.00:1 00. 2.2 4.7 Slightly brittle, brownish color Brittle, clear darkbrown. 1.00:1.00 Benzil and o-phenylenediamine..-.- 1.8 3. 5 Flexible,brownish orange Do.

tional solvent [m-cresol: xylene (1:1), 32 ml.] and the Example 10reaction mixture was stirred about 0.5 hr. at 25 C. to form a viscousyellowish orange solution. After stirring an additional 2 hrs. atambient temperature, the solution was divided into two equal portions.To one stirred portion, benzil (0.210 gm., 0.001 mole) was added as afine lowed by drying in a forced air oven at 60 C. for 18 hrs., 5

in vacuo from room temperature to 200 C. during 2 hrs., and at 200 C. invacuo for 4 hours. The resulting clear yellow films exhibited high tearresistance, tensile strength and flexibility.

The remaining portions of the polymer solutions were diluted withsolvent (1:1, m-cresol: xylene) and then separately poured slowly intomethanol in a Waring Blendor to precipitate yellow solids. The solidswere thoroughly washed in boiling methanol and dried at 150 C. in vacuofor 4 hours. The polymer decomposition tem- 4,5

peratures of each of the solids as measured by thermogravimetricanalysis at a heating rate of 6 C./min. in air and in helium wereessentially identical. However, the oxidative stability of theend-capped polymer as evidenced by isothermal weight loss measurementson powders mesh) and retention of film properties at 525 F. (274 C.) instatic air were improved as shown in Table VI.

The above procedure was also used to prepare a polymer from 18.93 gm.(0.098 mole) of 2,6-pyridinediyl 55 dihydrazidine and 43.45 gm. (0.100mole) of p,p'-oxydibenzil. The resulting yellowish orange solution wasdi- Tape was prepared by solution coating glass cloth carrier (112-A1100) with a m-cresol solution (20% solids) of the fourth final polymercharacterized in Tables land '11. The coated carrier was dried in aforced air oven at 300 F. to a volatiles content of less than 5%.Standard tensile shear specimens were then fabricated by assemblingtitanium (6A1-4V) panels with the coated carrier positionedtherebetween. The bonds were cured in an autoclave starting at roomtemperature and increasing the temperature to 550 F. duringapproximately 30 min. and maintaining at 550 F. for one hour under 35p.s.i. The resulting tensile shear specimens exhibited average roomtemperature strengths of 2500 p.s.i. and after aging for 2000 hours at500 F. in air, the average room temperature strength was 2100 p.s.i.

Example 11 A prepreg was prepared by impregnating a high modulus carbonfiber reinforcement material (Morganite I--- available from theWhittaker Corp.) with the polymer used in Example 10. The prepreg wasthen dried at 350 F. in vacuo to a total volatiles content of less than2%. Small (2 in. x 4 in. x 9 ply) unidirectional laminates werefabricated from the composite at 550 F. for one hour under 200 p.s.i.The resulting laminates had void contents of less than 1% and resincontents of about 28%. As indicated in the test data in Table VII below,thermoplastic failure occurred at elevated temperature for unpostcuredlaminates while laminates postcured in nitroge li through 2 hours at 550F. showed no thermoplastic a1 ure.

TABLE VH Flexure strength, p.s.i. Modulus, p.s.i.X10 Interlaminar shear}p.s.i.

Unpost- Unpost- Unpost- Test condition cured Postcured cured Postcuredcured Postcured Room temperature" 85, 000 30 32 5, 100 5, 400 300 F.after 10 min. 2 68, 000 84, 000 2 26 32 3 3,400 5, 100 500 F. after 10min 3 47, 000 81, 000 3 16 29 4, 800

1 Straight beam, span to depth r'atio 8:1. Thermoplastic failure.

vided into two equal portions and o-phenylenediamine Example 12 (1.081gm., 0.001 mole) was added to one of the stirred exhibited high tearresistance, tensile strength and flexi bility. The remainder of thesolutions were processed as described above and the results are shown inTable VI.

The above procedure was also used to prepare a poly- Films of thepolymer used in Examples 10 and 11 were prepared by doctoring a solution(-18% solids content) of the polymer in m-cresol onto a glass plate. Thesolvent was removed by drying in aforced air oven at C. for 10 hoursfollowed by heating to 150 C. in vacuo mer from stoichiometric amounts(0.100 mole) of 2,6- during 2 hours and maintaining at C. for 4 hours.

The clear lemon yellow film provided the properties shown in Table VII.

TABLE VIII Tensile Tensile Ultimate strength, modulus, elongation, Testtemperature p.s.i. p.s.i. percent Room temperature 17, 500 375, 000 4. 6177 C 13,400 250, 000 31.0

A random-type copolymer containing as-triazine and quinoxaline moietiesand a 1:1 distribution of units of the formulae F era-e and .N N. 1Hawai (and isomers thereof) was prepared by adding p-bis-(phenylglyoxalyl)benzene (3.424 gm., 0.010 mole) as a fine powder to astirred slurry of oxalamidrazone (0.569 gm., 0.0049 mole) and3,3'-diaminobenzidine (1.050 gm., 0.0049 mole) in a 1:1 mixture ofm-cresol and xylene (20 ml.) cooled in a water bath. After stirring at25 C. for min., a viscous clear red-orange solution formed whichincreased in viscosity and became orange during the next 0.5 hour.Additional solvent (10 ml.) was added and the resulting viscousyellowish-orange solution was stirred overnight. A portion of thesolution was used to cast a film on plate glass. After drying at 70 C.in air for 18 hours, followed by drying at 120 C. in vacuo for 2 hours,the clear yellow film was very tough and flexible. Another portion ofthe original polymer solution was poured into methanol in a WaringBlendor to precipitate a fibrous yellow solid. After thorough washing inhot methanol and drying at 130 C. in vacuo for 4 hours, the yellowpolymer exhibited an inherent viscosity (0.5% m-cresol solution at 25C.) of 1.03 dl./g., a glass transition temperature of 321 C. asdetermined by differential scanning calorimetry at a heating rate of 20C./min. in nitrogen, and a polymer decomposition temperature of 391 C.as determined by thermogravimetric analysis at a heating rate of 6C./min. in nitrogen. When exact stoichiometry was used in the polymerpreparation, the polymer solution gelled after sitting at roomtemperature overnight.

Example 14 A block-type copolymer containing pehnyl-substitutedas-triazine moieties and phenyl substituted quinoxaline moieties in a1:1 distribution was prepared by adding pbis(phenylglyoxalyl)-benzene(2.054 gm., 0.0060 mole) as a fine powder to a slurry of oxalamidrazone(0.5689 gm., 0.0049 mole) in a 1:1 mixture of m-cresol and xylene (10.5ml.). The mixture was stirred overnight at ambient temperature to yieldan orange oligomeric astriazine solution. In another flask,p-bis(phenylglyoxalyl) benzene (1.370 gm., 0.0040 mole) as a fine powderwas added to a slurry of 3,3'-diaminobenzidine (1.050 gm., 0.0049 mole)in a 1:1 mixture of m-cresol and xylene (10 ml.). After stirringovernight at ambient temperature, the reddish-orange oligomericquinoxaline solution was added to the as-triazine solution withstirring. The flask was washed out with additional solvent (5 ml.) whichwas added to the polymer solution. After stirring overnight at ambienttemperature, a portion of the viscous yellowish-orange solution was usedto cast a film which was dried as in Example 13. The clear yellow filmwas very tough and flexible. Another portion of the polymer solution wasquenched in methanol, thoroughly washed in methanol, and dried at C. invacuo for 4 hours. The fibrous yellow polymer exhibited an inherentviscosity of 1.51 dl./g., a glass transition temperature of 321 C., anda polymer decomposition temperature of 392 C., these properties beingdetermined as in Example 13.

Example 15 A poly-as-triazine consisting of recurring units of Formula Iwherein m is 0, R is p,p'-oxydiphenylene, and R and R are eachp-cyanophenyl, was prepared by adding p,p'-oxybis(p"-cyanobenzil) (2.422gm., 0.0050 mole) as a fine powder to a slurry of oxalamidrazone (0.569gm., 0.0049 mole) in a 1:1 mixture of m-cresol and xylene (12 ml.).After stirring at approximately 25 C. for 10 min., a viscous orangesolution formed and was stirred overnight. A portion of the viscousorange solution was used to cast a film which, after drying, was verytough and flexible. The remainder of the polymer solution was quenchedin methanol in a Waring Blendor to precipitate a fibrous yellow solid.After washing in methanol and drying at 130 C. in vacuo for 4 hrs., thefibrous yellow solid exhibited an inherent viscosity of 1.15 dl./g., aglass transition temperature of 285 C.,

and a polymer decomposition temperature of 394 0., these propertiesbeing determined as in Example 13. It will be apparent that the nitrilesubstituents in the polymer so prepared can be readily hydrolyzed tocarboxyl groups which can in turn be converted to acid chlorides byreaction with thionyl chloride. The acid chlorides can in turn bereacted with alcohols and amines to produce esters and amides,respectively. The p,p'-oxybis(p"-cyanobenzil) employed in the foregoingprocedure was prepared as follows. p-Cyanophenylacetic acid was obtainedby diazotizing p-aminophenylacetic acid and coupling the diazonium saltwith cuprous cyanide. p-Cyanophenylacetic acid was converted to the acidchloride with thionyl chloride. A solution of the acid chloride anddiphenyl ether in methylene chloride was added to a slurry of anhydrousaluminum chloride in methylene chloride at 5-8 C. The resulting redreaction mixture was poured onto ice and hydrochloric acid. The organicphase was separated, washed with water, dried over calcium sulfate, andconcentrated to yield a brown residue. Recrystallization from ethanolprovided the intermediate diketone as a pale yellow granular crystallinesolid (M.P. 186-188 C.), which was oxidized with selenium dioxide inglacial acetic acid to afford the p,p-oxybis(p"-cyanobenzil).Recrystallization from a mixture of alcohol and benzene afforded ayellow crystalline solid, M.P. 183-185 C. with decomposition (solidifiesthen remelts at 201 C.). The infrared spectrum exhibited a sharp band at4.5,u characteristic of nitrile group. Elemental analysis gave thefollowing results.

Analysis.Calcd. for C H N O (percent) C, 74.37; H, 3.33; N, 5.78. Found(percent): C, 74.28; H, 3.36; N, 5.66.

Example 16 oxalamidrazone was separately reacted with stoichiometricquantities of seven bis-(1,2-dicarbonyl) compounds to producepoly-as-triazines consisting of recurring units of Formula I, wherein mis 0, R R, and R are as in- 17 dicated in Table IX. Polymers 1-3 (seeTable IX) were prepared in m-cresol at 20% solids content andtemperatures of approximately 70 C. During preparation of polymet 1, thepolymer precipitated from solution as an orange solid. At solidscontent, the polymer failed to dissolve completely in m-cresol,hexamethylphosphoramide or dimethyl sulfoxide. Polymers 2 and 3 readilyformed viscous solutions at 20% solids content in m-cresol, but failedto form complete solutions in hexamethylphosphoramide or dimethylsulfoxide at 5% solids content. Polymers 4-7 were prepared in highmolecular weigth form in a 1:1 mixture of mcresol and xylene, at roomtemperature and at solids content of In each case, a clearyellowish-orange, viscous solution formed on a 0.010 molar scale afterapproximately 0.5 hr. Tough, flexible, transparent, yellow films werecast from these solutions.

TABLE IX in, TE Polymer No. Formula I ('m=0) R2 and Ba l./g. C.

1 p-Phenylene Hy 0. 65 260 2. p,p-Oxydiphenylene -d 1. 48 244 3. p,pThiodiphenylen 1. 52 240 4 m-Phenyleue- 1. 47 295 5. p-Phenylene....1.32 302 6. p,p-Oxydiphenylene do 1.96 270 7 p,p-Thiodiphenylene .-do1.85 260 1 0.5% m-cresol solution at 25 C. a Glass transitiontemperature determined by differential scanning calorimetry at a heatingrate of 20 C./min. in nitrogen.

What is claimed is: 1. Poly-as-triazines consisting essentially ofrecurring units of the formula N (R)mJO |-Rl \NTRsj wherein m is 0 or 1;R is a divalent radical selected from (CH and (CF where y is an integerof from 1 to 12; R is a divalent radical selected from and (CH where zis an integer of from 2 to 12; and R and R are monovalent radicalsindividually selected from alkyl of 1 to 12 carbon atoms, phenyl, andsubstituted phenyl wherein the substituents are substantially inert.

2. Poly-as-triazines of claim 1 wherein R and R are each phenyl.

3. Poly-as-triazines of claim 2 wherein m is 0 or 1;

R is selected from aria and --(CF where y is an integer of from 1 to.12; and R is selected from 4. Poly-as-triazines of claim 1 furtherconsisting essentially of recurring units of the formula tog wherein R Rand R are as defined in claim 1 and R is a tetravalent radical selectedfrom where X is selected from -0, S, SO--, SO;;, -C0, CH and 5.Poly-as-triazines of claim 1 consisting essentially of at least 20 ofsaid units.

6. Poly-as-triazines consisting essentially of recurring units of theformula wherein m is 0 or 1; n is an integer of at least about 20; R isa divalent radical selected from and (CH-,,),, where y is an integer offrom 1 to 12; and R is a divalent radical selected from and (CH where zis an integer of from 2 to 12.

7. Poly-as-triazines of claim 6 wherein R is selected ease-as and --(CFwhere y is an integer of from 1 to 12; R is selected from 8. A processfor the preparation of poly-as-triazines consisting essentially of atleast recurring units of the wherein m is 0 or 1; R is a divalentradical selected from 0' 0 00 1 0 0 0 0- 61.1- two-non (CH and (CF wherey is an integer of from 1 to 12; R is a divalent radical selected fromCHa and (CH where z is an integer of from 2 to 12; and R and R aremonovalent radicals individually selected from hydrogen, alkyl of l to12 carbon atoms, phenyl, and substituted phenyl wherein the substituentsare substantially inert; comprising reacting a dihydrazidine of theformula HN NH H it it 2NHN R NHNIIz with a bis-(1,2-dicarbonyl) compoundof the formula in a solvent selected from the group consisting ofmcresol, anisole, pyridine, chloroform, sym-tetrachloroethane, mixturesthereof and mixtures of Xylene or toluene with m-cresol orsym-tetrachloroethane.

9. The process of claim 8 wherein said solvent comprises m-cresol.

10. The process of claim 8 wherein R and R are each phenyl.

11. The process of claim 10 wherein said solvent comprises m-cresol.

12. The process of claim 8 wherein m is 0 or 1; R is selected from and(CF where y is an integer of from 1 to 12; R is selected from easeso eand R and R are each phenyl.

13. The process of claim 12 wherein said solvent comprises m-cresol.

14. The process of claim 8 wherein the quantity of said dihydrazidine isfrom 0.975 to 1.025 mole per 1.000 mole of said bis-(1,2-dicarbonyl)compound.

15. The process of claim 14 wherein R and R are each phenyl.

16. The process of claim 8 wherein the quantity of said dihydrazidine isfrom 0.990 to 1.010 mole per 1.000 mole of said bis-(1,2-dicarbonyl)compound.

17. The process of claim 8 wherein the quantities of dihydrazidine andbis(l,2-dicarbonyl) compound are in proportions of from 0.975 to 0.995mole of one per 1.000 mole of the other.

18. The process of claim 17 wherein R and R are each phenyl.

19. The process of claim 18 wherein said solvent comprises m-cresol.

20. The process of claim 8 further comprising reacting saidpoly-as-triazine with at least one compound selected from benzil,benzoyl chloride, o-phenylenediamine, and 2-pyridylhydrazine wherebythere are formed as-triazine, 1,2,4-triazole or quinoxaline end groupsthereon.

21 22 21. The process of claim 8 wherein R and R are inand R and R areeach phenyl or substituted phenyl. dividually selected from alkyl,phenyl, and substituted 25. The process of claim 8 wherein m is 1, R isphenyl.

Poly-as-triazines of claim 6 wherein m is 1 and R 1s 5 O N 6 R1 is N 1023. Poly-as-triazines of claim 6 wherein m is 1, R is 0 5 and R and Rare each phenyl or substituted phenyl.

and 1 is References Cited UNITED STATES PATENTS O 6 3,594,349 7/1971Culbertson 260-42 3,021,328 2/1962 Morin et a1. 260248 24. The processof claim 8 wherein m is 1, R is LESTER L LEE Primary Examiner 0 US. Cl.X.R.

25 117-124 E; 161-257 26032.6 N, 33.4 P, 33 XR, 51.5,

- ew UNITED S'IA'lIsJS PATENT OFFICE CERTIFICATE OF CORRECTION PatentNo. 3,778,412 Dated December 11, 1973 7 Inventofls) l. M. HergenrotherIt is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Claim 8, column 19, lines 59-63, change the third formula from to column20, lines 1-5, change the first three formulae e @EDE} 3 CH2 '5 I I I 7@CH Signed end sealed this 20th day r August 197 from (SEAL) Attest:

McCOY M. GIBSON, JR." C; MARSHALL DANN L Attesting Officer Commissionerof Patents J

